Advice on writing a story!

I'm currently stuck on my first story ever. I don't know what to write anymore :( But I got an idea for another story so I've already started writing the first chapter. Its far from finished though. I need to organize my ideas first.

I was wondering you guys' take on some story writing basics.

1. Do you like to find pictures of the characters? Or would you rather make them up in your mind?

2. Do you like when the story has a couple of different points of view?

3. Do you like short or long chapters?

4. How important are details in a story? I find myself not good at detailing.

Please let me know what you think :)

I'm looking to improve my writing so this would be really helpful.

Any other advice you can give me will be well received!